Analyzing most typical energy saving measures Energy Efficiency of Steam and Condensate Systems Antero Punttila, Motiva

1. Analyzing most typical energy saving measures • Energy Efficiency ofSteam and Condensate Systems • Antero Punttila, Motiva Oy. Antero Punttila 10.12.2007

2. Steam systems in industry and other sectors • Steam can be used for heating, drying, moistening and sterilization of products in industry and other fields • Steam has advantages in effective heat transfer, indirect or direct heating and hygienic. • Special attention shall be given in productivity of steam production (exhaust gas and blowout losses), distribution networks and steam users. • Water treatment and high maintenance needs may increase operating costs. Antero Punttila 10.12.2007

3. 2. Steam production • Steam can be produced by steam boilers and steam generators. • Key factors in economic steam production • boiler plant • continuous consumption monitoring • skilled personnel • Considerations in boilers • boiler capacity meets steam requirements • meters are in good condition • out-blow is not excessive • economizer is in operation • heat transfer surfaces are clean • boiler has no air leakages • boiler insulation is in good condition Antero Punttila 10.12.2007

4. 3. Steam networks • Steam use can be either direct or indirect, but the used energy amount is the same, but heat losses may differ. • In direct use the valuable condensing water return shall be checked regularly • Superheated steam has lower heat transfer coefficient than saturated steam • Moist steam stress equipment more than dry steam • Air mixed in steam reduces the heat transfer coefficient Antero Punttila 10.12.2007

5. 4. Leaks • Leaks in steam systems • waste continuously energy (24/7) • reduce network pressure and energy flow • waste valuable condense water (treated water) • reduce work safety (blasts) • To be checked visually or with ultrasonic detector • safety valves, steam traps, orifice connectors, gate valves, unattended pipe-tunnels • leakage inspections shall be made at least twice per year Antero Punttila 10.12.2007

6. 5. Pipe and equipment insulation • Pipes, flanges, equipment and valves shall be insulated because of heat losses and working safety • Condense pipes always insulated, except condense valves • Wet insulation causes energy waste and outside corrosion • Un-insulated DN 200 valve may have up to 200 C temperature and 5 kW continuous heat loss Antero Punttila 10.12.2007

7. 6. Condense return • Condense return is important in indirect steam use. Condense traps are important. • Precise condense return causes: • good utilization of condense heat content • reduction in make-up water needs • Closure of open condense tank causes • reduction in heat loss • reduction in tank corrosion • Condense tank should be blanketed from oxygen entry by steam etc Antero Punttila 10.12.2007

8. Failures in condense traps • Condense return rate shall be monitored and maximized • Fault trap causes steam-condense mix in condense pipe leading to increased temperate and backpressure, increased steam consumption, higher condense and high feed water pumping costs • Faults in condense traps should be seek by listening (man / machine) and by temperature metering (every 2 to 4 months) Antero Punttila 10.12.2007

9. 5. Utilization of blowout steam (expansion steam) • Benefits of blowout • Reduced steam consumption • Lost blowout steam reduces • Capacity of condensing network increases • Utilization of blowout steam • Blowout steam usage in low pressure systems • Preheating of combustion air, compressed air and rooms • Heating of sub-cooled condense or preheating of process-water in condense tank Antero Punttila 10.12.2007

10. 6. Economical use of steam • Steam pressure • Is defined by required temperature /pressure level • It is important that temperature/pressure meets the user requirements • It is important that pressure fluctuation is as small as possible • Steam networks can be divided by pressure reduction valves to different pressure subnets Antero Punttila 10.12.2007

11. Equipment considerations • Very important that process automation works properly • Steam network and equipment shall be started slowly • Steam heated equipment shall have thermal insulation • Open liquid surfaces shall be covered against evaporation • Bypass valves shall be kept closed and watertight • Minimization of steam pressure, finally replacing steam with hot water • Drying first by mechanical water removal, then steam-drying and avoid over-drying • Avoid unnecessary stand by use of steam systems Antero Punttila 10.12.2007

12. More information on new direction of energy-use: www.motiva.fi Antero Punttila 10.12.2007